The present invention relates to a composition for a sizing agent comprising a mixture of a substituted alkyl succinic anhydride or a substituted alkenyl succinic anhydride or a mixture of these succinic anhydrides, phosphates of polyoxyethylene alkyl esters or phosphates of polyoxyethylene alkyl aryl ethers or a mixture of these phosphates of esters and a process for using the composition for the sizing agent by dispersing the composition in aqueous solution of aqueous soluble polymer compound, adding the obtained aqueous dispersant in a pulp slurry of paper making raw material, and making paper and, more particularly, to a composition for sizing paper having excellent storage effect and preferable underwater self emulsion, and a process for making paper having excellent sizing effect by using the composition.
There is known a sizing agent and particularly a paper making sizing agent such as a mixture homogenized by mechanically agitating an aqueous solution of cationic starch and a substituted succinic anhydride in an aqueous dispersion to be mixed with a pulp slurry, a dispersion of mixture of premixing a substituted succinic anhydride and nonionic surfactant of certain type in water (in Japanese Patent Publication No. 36044/1978), or an aqueous dispersion of a substituted succinic anhydride and underwater oil type surfactant dispersed in a substituted succinic anhydride having diameters of ultrafine particles dispersed an aqueous solution of ampholitic acrylamide polymer (in Japanese Patent Laid-open No. 45,731/1983). A large scale apparatus is required in the case of producing the dispersion by using cationic starch of these aqueous dispersions, and yet it is difficult to sufficiently finely pulverize the dispersion particles in the obtained aqueous dispersion. Therefore, the sizing agent has a drawback that the sizing effect of the dispersion is deteriorated, and the aqueous dispersions of the latter two having inadequate storage stability of the composition before the aqueous dispersion of the latter two is dispersed in the aqueous dispersion, and as time is elapsed, the under water dispersant is erased, and the sizing performance is largely decreased. Consequently, the mixture compostion must be adjusted immediately when used as the sizing agent, and there is a problem in a practical use in an industrial scale.
In order to solve the above-described problems, the present inventors have proposed an aqueous dispersion containing a surfactant having a substituted succinic anhydride and a half ester residue of the substituted succinic acid (in Japanese Patent Application No. 154984/1982), but in the aqueous dispersion, when a substituted alkenyl succinic anhydride of an additive reaction product of a straight chain internal olefin and maleic anhydride is used as the substituted succinic anhydride, sufficient underwater dispersing effect cannot be obtained unless the above-described surfactant is mixed in large quantity, and since the large quantity of the surfactant substance disturbs the sizing effect. Therefore, it is found that excellent sizing effect cannot be obtained.